Safety unit



- Jan. 6, 1959 Q AJLEFEBVRE 2,867,020

SAFETY UNIT Filed Nov. 13. 1953 1N VEN TOR.

Alien Lefebiav a W126! m%.

' ATTD RN E Y5 nited States 2,867,020 SAFETY UNIT Albert Lefebvre,Johnston, R. I.,assignor of one-half to William Jakober, Cranston, R. I.

This invention relates to a scaffold, and more particularly to a safetyunit for a scaffold.

The object of the invention is to provide a safety unit which willsafely lock a load such as a scaffold in any position to which it may beadjusted.

Another object of the invention is to provide a unit which will preventthe falling of the scaffolding in case the usual hoisting tackle breaksor-becomes accidentally released.

A further object of the invention is to provide a safety unit which isextremely simple and inexpensive to manufacture.

Other objects and advantages will be apparent during the course of thefollowing description.

In the accompanying drawings, forming a part of this application, and inwhich like numerals are used to designate like parts throughout thesame:

Figure l is an end elevational view showing a scaffold with the presentinvention attached thereto.

Figure 2 is a horizontal sectional view taken through the scaffold cableand showing the present invention.

Figure 3 is a side elevational view of the casing, with parts brokenaway and in section.

Figure 4 is a view similar to Fig. 3 with certain parts removed and withthe unit in releasing position.

Figure 5 is an end elevational view of the unit.

Figure 6 is a sectional view taken on the line 6-6 of Figure 2.

Figure 7 is a sectional view taken on the line 7-7 of Figure 9.

Figure 8 is an elevational view of the wedge and cam on the shaft.

Figure 9 is a view taken at right angles to the view shown in Figure 8.

Referring in detail to the drawings, there is shown a portion ofascaffold which includes an upper pulley 10 and a lower pulley 11, therebeing cables 12 extending between the pulleys 10 and 11. Suitablebrackets 14 may be arranged below the pulley 11, and a horizontallydisposed platform 15 may be supported by the brackets 14. Arms 16 may besecured to each of the lower pulleys 11.

The present invention is directed to a safety unit 17 which will serveto maintain the scaffold immobile in its various adjusted positions andwhich will also serve to prevent the scaffold from falling in the eventthat one of the cables accidentally breaks. The safety unit 17 comprisesa casing or housing, and one of the casings may be provided for eachside of the scaffold or for each upper and lower pulley. The casing maybe made of a single piece of suitable material such as metal, and mayinclude spaced apart side members 18 which each include a flat portion19. The fiat portions 19 are interconnected together by an arcuate web20. Arranged at right angles with respect to each fiat portion 19 is astraight section 21, and extending from each straight section 21 is afiat portion 22. Overlapping end portions 23 extend inwardly from theflat portions 22 and are interconnected securing element such as a screw28. A coil spring 30 has one end connected to a pin 29 which extendsfrom the shaft 26, and the other end of the coil spring is com nected toa pin 33 that extends from the adjacent side member. Anopening 13 may beprovided in an end I of the shaft 26 for receiving the pin 29, and theshaft 26 may also be provided with a reduced diameter portion 9 forattachment to the lever or handle 27.

Interposed between the flat portions 19 is a rotatable cam or wedge 34which may be knurled exteriorly, and the wedge 34 is secured to theshaft 26 by a key or pin 35. The wedge 34 may be provided with anarcuate recess 36 for at times engaging a portion of the cable 12.

From the foregoing it is apparent that a safety.unit has been providedwhich will maintain a scaffold immobile in its various adjustedpositions and which will prevent the platform 15 from falling eventhough one of the cables may break. In use when the platform 15 is to beraised or lowered, it is onlynecessary to manually grip the lever handle27 and pivot it in a counterclockwise direction from the position shownin Figure 34 out of engagement with the cable 12 after it has been movedtherefrom, and the spring 30 also serves to maintain the wedge 34 intolocking engagement 12 when the parts are in the position shown in Figure2. The spring 30 is able to function to thus maintain the device lockedor unlocked since it is connected off center to the shaft 26. Theknurling and recess 36 on the Wedge 34 help to provide a more positiveand safer lock between the wedge and the cable. The numeral 13designates an opening in the shaft 26 which may receive the pin 29, andan end of the shaft 26 is of reduced size as at 9 for engagement withthe lever 27. A cover 31 may be secured to one of the side members bysuitable screws 32 and the cover 31 serves to enclose and protect themovable spring 30 and its associated parts.

The unit of the present invention is a separate unit from the block andtackle assembly and the present invention can be readily installed orremoved from the block and tackle. One or two of the bolt and nutassemblies 25 can be used for connecting the casing to the straps 16.The present invention does not lock the main lines but locks one of thelines 12 in the back which extends between the upper and lower pulleys.The present invention can be used for any type work wherein a scaffoldis needed and can be used on any type building and is simple andinexpensive to manufacture. The present invention can be used bypainters, steeple jacks and the like. With the present invention thescaffold can be raised without unlocking the safety unit, but it cannotbe lowered without unlocking the safety unit. The size of the parts canbe varied as desired.

I claim:

In a safety unit for a cable of a block and tackle, a casing including apair of spaced apart side members each including flat portionsinterconnected together by an arcuate web which is positioned incircumjacent rela tion to the cable, a straight section extendingoutwardly at right angles with respect to each flat portion, flatsections extending from each straight section, and over- Patented J an.6, 19 59' lapping end portions extending inwardly from said flatsectionsv andsecured together, .ashaft extending ,rotatably through saidflat portions and having a reduced diameter portion, an exteriorlyknurled earn secured to said shaft and interposedrbetweensaid pair of..flat, portions for ,engagementawith the..cable, ansL-rshapedpin mountedin said. shaft. and extending from said shaft :and :outwardly fromone..of.said side members, a coil spring connected to said pin andtosaid oneside member, said spring serving to maintain said cam immobile.in its adjusted-positions in engagement with the cable, and a coverenclosing said'coilspring, a handle secured to the reduced diameterportion of said shaft, said cam having an arcuate recessed portion forengagement withthe cable, said handle being arranged on the oppositeside of said casing from said cover, the sides of said cam frictionaliya d snu y n a n t e sinne s a o said flat p tions.

References Cited in the file of this patent UNITED STATES PATENTS McKayMay 18, Sturges July 22, Livingston Nov. 7, Morgan June 16, Koorie July24, Christensen Nov. 16, Regar Dec. 14, Gluyas June 22, Arnzen Mar. 8,Walter June 9, Dale May 18, Hauer Feb. 20, Winslow Feb. 10, Storer Feb.22, Orton May 24, Adams Ian. 3,

